A.NaCl+H3A B.NaCl+NaH2A C.NaCl+Na2HA D.NaCl+Na3A
A.+0.02% B.+0.01% C.-0.02% D.-0.01%
A.5.62×10-10 B.3.2×10-10 C.8.4×10-9 D.7.1×10-8